1. Field of the Invention
This invention relates to control and measuring instruments and, in particular, to methods and videomonitors for non-destructive quality inspection of materials.
The invention can be used in the oil and gas industry for pipe weld quality testing, in machine building for detecting flaws in rolled products, in ship building for quality testing of welded ship hulls and tanks, and in other fields where products have to be tested for continuity defects. It can also be employed in medicine and biology for storage, processing, and visualization of information on biological objects.
2. Description of the Prior Art
Known in the art is a method for non-destructive quality inspection of materials (U.S. Pat. No. 3,341,771; Cl. 324-213), comprising the steps of magnetizing the material to be inspected, a magnetic recording medium being placed on the surface on this material, then removing said magnetic medium which through the action of the magnetizing field had recorded a magnetogram which contains information on the quality of the material being tested, and placing the magnetic medium into a device for recording said magnetogram, in which the pick-up is positioned near the surface of the magnetic medium and their relative motion is ensured. Information sensed by the pick-up is converted into electrical signals which are used to assess the quality of the material.
The apparatus realizing this method comprises a magnetic pick-up capable of reciprocating motion above the surface of the magnetic medium, an amplifier, and an indicator. The indicator is a cathode-ray tube displaying a pulse signal whose shape is used to assess the quality of the material being inspected.
However, this method and apparatus realizing the method are deficient in that they can only be used to detect a flaw in the material being inspected. They cannot furnish any 3-D characteristics of this flaw, such as the depth, shape, length, relative position.
Also known in the art is an ultrasonic flaw detector USDl manufactured by KRAUTKRAMER in the Federal Republic of Germany "(Booklet of Krautkramer, Production Program for 1984-1985, p.7)". In this device a data transmitter is an ultrasonic transducer placed on the surface of the material to be tested and their relative motion is ensured. Information fed by the transmitter is processed in the built-in microcomputer and displayed on the screen of the cathode-ray tube as an image of echo signals and as digital data on the depth of the flaw and the distance from the transducer to the projection of the flaw on the surface of the tested product.
But the aforementioned device is deficient in that it cannot provide a shadow-color image indicative of the quality of the material being tested. It also cannot provide prompt information on the amount and relative position of flaws in the material, their length and configuration.
The closest prior art is a method for non-destructive testing (cf., for example, U.S.S.R. Inventor's Certificate No. 456,572; 1974) whereby information fed by a pick-up, which is indicative of the quality of the material being tested, is subjected to scale and time conversion by entering this information to a storage unit in synchronism with the motion of the pick-up relative to the tested material, and then displayed on the screen of a cathode-ray tube, while the recording is simultaneously read from the memory.
There is known a videomonitor realizing this method (cf., for example, G. R. Kreps, Forming Television Signals in Flaw Detectors Using Automatic Mechanical Scanning, Defektoskopiya, 1979, No. 6, pp. 106-109) which comprises several series-connected components: a data transmitter mounted on a device which scans this transmitter in relation to the tested material, an analog-digital converter, a memory, a digital-analog converter, and a display which is a color electron beam tube; a recording counter connected in series to a switch whose output is connected to the memory, a readout counter whose output is connected to a second input of the switch, a control unit connected to the synchronization input of the data transmitter and to inputs of the recording counter, the readout counter, the analog-digital converter, the memory, the switch, and the digital-analog converter, a synchronization output of the scanning device being connected to the other input of the recording counter.
However, the aforementioned device is deficient in that it cannot provide continuous display of information on the quality of the tested material when the pick-up is transported in relation to this tested material for a long distance. This device also cannot provide a prompt increase in the resolution of the color picture for the detailed analysis of the material quality. It also cannot help determine precisely the coordinates and length of a defect.
The term "data transmitter" used here and henceforth in this description means a flaw detector equipped with a pickup. It is evident that the pickup is placed near the surface of the tested material on a scanning device, while information and timing signals are fed from the outputs of the flaw detector.